Panarctic Flora

410718 Rumex oblongifolius Tolm.

• Tolm., Fl. Arct. URSS 5: 154 (1966). Holotype (LE)?: Siberia: Yakutia, "ad flumen Tenkaczan, in parte meridionali jugi montium Verkhojanski chrebet dicto", 18. July 1936, leg. M. Jarovoi. - Acetosa oblongifolia (Tolm.) Á. Löve & D. Löve, Bot. Not. 128: 506 (1976).

Geography: Asian (NE): RFE.

Notes: Elven and Murray: Subgenus Acetosella includes three groups in the northern regions: (a) Rumex acetosella, (b) R. graminifolius + R. aureostigmaticus, and (c) R. beringensis + R. krausei.

(a) Rumex acetosella is characterized by rhizomes horizontal and often richly branched, ochreas silvery hyaline, blades normally with basal lobes, and inner tepals not much enlargening in fruit stage. The species is mainly temperate-boreal, European to western Siberian but some races are spread as weeds in all temperate and boreal (and austral) parts of the world. Rumex acetosella included at least the taxa named "acetosella" s. str., "tenuifolius", "acetoselloides" (southern), "pyrenaicus" (southern), and "multifidus" (= "angiocarpus" southern). A large amount of work has been done on these plants, partly of an experimental nature (see references in Elven 2000 and Mosyakin 2005). Löve (1940a, 1940b, 1941a, 1941b, 1943) stated that some of the taxa were distinguished by strongly correlated morphological differences and ploidy levels, his tetraploid Acetosella tenuifolia, his hexaploid Acetosella vulgaris (= R. acetosella s. str.), and some diploid southern plants. These correlations have later been questioned in several investigations. Presence of two or more ploidy levels are now assumed within at least some taxa even if there is no more modern study comparing the morphology of plants at different ploidy levels. The taxa "acetosella" and "tenuifolius" are still partly recognized on morphological evidence but then as subspecies. Due to the often opposing conclusions of the numerous investigations, few current investigators accept the taxa as species any more.

One taxon of this group is more enigmatic as to affinity. Subspecies arenicola was described from Greenland and is known from arctic and alpine sites in the northern amphi-Atlantic regions. It has therefore been treated according to this regional tradition as a race of R. acetosella and has not been compared with the northern Russian, Siberian, and Beringian plants. However, the main diagnostic characters in flowers and fruits suggest that its closest affinity is within R. acetosella.

The other native northern plants belong to the two other groups (b and c).

(b) Rumex graminifolius and R. aureostigmaticus are characterized by rhizomes vertical and richly branched, ochreas silvery hyaline and remaining for a long time on the basal branches, blades very long and narrow and mostly without basal lobes, inflorescences richly branched, and inner tepals strongly enlargening in fruit stage. Collectively, these two species have a boreal to arctic, almost exclusively Eurasian range with very few adventive occurrences. The two species we accept may alternatively be treated as two subspecies but subspecific combinations are not available, and there are no indications of transitions (but also very few investigations).

(c) Rumex beringensis and R. krausei are characterized by rhizomes short and little branched, ochreas brown and broad and often persistent, narrow blades mostly without basal lobes, inflorescence less to not branched, and inner tepals not much enlargening even in fruit stage. The two species are largely sympatric in the North Pacific to amphi-Beringian regions and with no observed transitions.

Much confusion has resulted from different applications of the name R. graminifolius. Áskell Löve followed a tradition from, e.g., Kjellman (1883) and Hultén (1937, 1944) and applied this name (as Acetosella graminifolia) to some short-grown (and short-leaved) arctic plants of gravelly ground and outcrops. Kjellman's and Hultén's plants were Beringian and belong to either R. beringensis or R. krausei in the current view. The information Löve published under the name Acetosella graminifolia refers to plants from Greenland (R. acetosella subsp. arenicola), northern Norway (R. graminifolius and R. acetosella subsp. arenicola), arctic European Russia (R. acetosella subsp. arenicola), and Beringia (R. beringensis and R. krausei). Also his list of octoploid chromosome counts (Löve and Löve 1975a) is referable to several taxa. Rumex graminifolius as described and illustrated by Lambert, based on a plant most probably collected in southeastern Siberia, is a mainly boreal plant differing in several features from the arctic plants named as such by Löve. Rumex graminifolius and the quite similar R. aureostigmaticus are as different morphologically from R. beringensis and R. krausei as they are from R. acetosella s. lat.

The taxa named "arenicola", "graminifolius", "aureostigmaticus", "beringensis", and "krausei" together constitute a boreal to arctic, nearly circumpolar group of native plants, most diverse in Beringia. These are the truly arctic representatives of subg. Acetosella. The reasons why they have been merged, by Löve and many others within the concept of R. graminifolius, are that their blades are narrow and entire or subentire and that they (except for R. acetosella subsp. arenicola) have large nuts and tepals (valves) distinctly longer than the nut.